The invention relates to a device for producing smooth finished concrete corners and joints, while reducing the time, labor, expense and expertise required in making such a corner or joint. This invention is particularly related to concrete joints between the tread and the riser of stair steps and concrete corners of walls.
In the current method of making concrete formwork for producing steps, as shown in FIG. 1, the formwork 100 for the riser of the step is typically made from a wooden plank, such as a 2.times.8 or a 2.times.10. This plank 100 is typically attached to the sides of the formwork by nailing. As the concrete is poured, the surface for the tread of the step 102 is levelled and smoothed by trowelling with a trowel 104. To allow enough room for the trowel 104 to smooth the joint more closely to the corner, the edge of the formwork plank 100 is typically ripped at an angle, shown at 106. This angle 106 is typically approximately 45.degree.. However, because of the appreciable thickness of the trowel 104 and the riser formwork, it is not easy for the trowel 104 to smooth the concrete all of the way up to the final finished corner, as shown by the open space 108 between the formwork 100 and the trowel 104. There will always be some loose stone or concrete which floats into the open space 108 and is not removed with the trowel 104 These stones and concrete make the finished joint rough and aesthetically undesirable. An experienced concrete finisher can limit this roughing to some extent, but this requires a great deal of time and experience in concrete work, which increases the costs. Furthermore, it takes extra time to rip the formwork 100 at the angle 106, thus ruining the 2.times.8 or 2.times.10, which also increases the costs.
If the concrete is of poor quality, for example, either too pasty, too watery, or already beginning to set up, it becomes even more difficult and more time consuming to produce a smooth finished joint Weather conditions, such as rain, can cause puddles and deteriorate the finish of the concrete joint During vibration of the steps, for properly settling of the concrete, the joints can be deteriorated. Furthermore, it may be necessary to re-trowel the treads and re-smooth the corners, thus adding additional time, labor and expense Improper vibration can cause honeycombing at the joints, which provides an undesirable finished joint.
Likewise, when producing concrete walls, the corners of the formwork are formed by nailing two sheets of plywood together to form a corner joint. If these corner joints are not held tightly together, stones and concrete work their way into the corners, especially after numerous pourings of concrete, thus loosening the joint. The final corners appear rough and uneven, which detracts from the appearance of the finished corner.